Updating json array of objects in Oracle

Question

Hi I have a json column in Oracle database with a data like [{"id":100, "make":"BMW"},{"id":110,"make":"mercedes"}]..... now how can I update the make of object with id 110 to Toyota using sql/plsql..Thank you..

Answer 1

You can use json_table() function for version 12.1.0.2+ to parse a json column. Btw, a string type column such as clob , varchar2 might be checked out by adding a check constraint for concerned string type column. So use :

update tab
   set jsdata=(select case when js.id = 110 then replace(jsdata,js.make,'toyota') end
                 from tab
                cross join
                      json_table(jsdata, '$[*]'
                         columns(make    varchar2(50) path '$.make',
                                 id      int path '$.id')) js
                where js.id = 110   ) 

Demo

Answer 2

Unfortunately, it is not easy to change data within an array.

create table t(
  id number primary key,
  json_ds varchar2(4000) check(json_ds is json)
);
insert into t values (1, '[{"id":100, "make":"BMW"},{"id":110,"make":"mercedes"}]');
commit;

update /*+ WITH_PLSQL */ t a
set json_ds = (
  with function update_json(p_in in varchar2) return varchar2 is
    l_ja json_array_t;
    l_po json_object_t;
    l_id number;
  begin
    l_ja := json_array_t.parse(p_in);
    for i in 0..l_ja.get_size - 1 loop
      l_po := json_object_t(l_ja.get(i));
      l_id := l_po.get_number('id');
      if l_id = 110 then
        l_po.put('make', 'Toyota');
      end if;
    end loop;
    return l_ja.to_string;
  end update_json;
  select update_json(a.json_ds) from dual
)
where id = 1;
/
select * from t;

ID  JSON_DS
1   [{"id":100,"make":"BMW"},{"id":110,"make":"Toyota"}]

Best regards, Stew Ashton

Answer 3

You can use JSON_TRANSFORM() in 19.8 and up.

with example as
 (select '[{"id":100, "make":"BMW"},{"id":110,"make":"mercedes"}]' as json from dual)
select json_transform(example.json, set '$[*]?(@.id==110).make' = 'Toyota') as newjson from example;

Output:

[{"id":100,"make":"BMW"},{"id":110,"make":"Toyota"}]

You can also use JSON_MERGEPATCH (19c and up) but it can't update within arrays, need to update the whole array

Regards